Method of providing a virtual space image subjected to blurring processing based on detected displacement, and system therefor

ABSTRACT

A method including generating a virtual space image for displaying on a head mounted display (HMD). The method further includes acquiring a rotational direction and a rotational speed of the HMD. The method further includes subjecting the virtual space image to blurring processing based on the rotational direction and the rotational speed, the blurring processing being performed on end regions of the virtual space image on both sides of the virtual space image in a direction corresponding to the rotational direction, a size of the end regions corresponding to the rotational speed, and an intensity of blurring of the end regions corresponding to the rotational speed.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/422,426 filed on Feb. 1, 2017, which claims priority toJapanese Patent Application No. 2016-017825 filed Feb. 2, 2016. Thedisclosures of all of the above-listed prior-filed applications arehereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

This disclosure relates to a method of providing a virtual space imageto be visually recognized by a user to a head mounted display(hereinafter referred to as “HMD”), and a system therefor.

BACKGROUND ART

In Patent Literature 1, there is described a method involving detectingan angular velocity of the movement of an image pickup apparatus andperforming filter processing in which a blur amount for an outerperipheral part or a peripheral edge part with respect to a central partis set based on the angular velocity, to thereby prevent visuallyinduced motion sickness.

PRIOR ART DOCUMENT Patent Literature

-   [Patent Literature 1] Japanese Patent Application Laid-open No.    2007-116309

SUMMARY

However, the image pickup apparatus in Patent Literature 1 is placed ina real space, and does not presuppose a special audiovisual environmentexhibited when, for example, a user wearing an HMD is immersing himselfor herself in a virtual space. This disclosure helps to reduce visuallyinduced motion sickness (so-called VR motion sickness) caused whenvirtual reality (hereinafter referred to as “VR”) is provided with useof an HMD.

In the method described in Patent Literature 1, a characteristicdetecting unit detects a motion vector of a portion to be detected basedon an input image signal acquired from a stereoscopic camera, to therebydetermine the magnitude of the movement of the image. Then, an imagequality is reduced in accordance with the result of the determination,to thereby reduce a visual load on an observer.

However, Patent Literature 1 does not support a case where a user'svisual field in a VR space is synchronized with the movement of the HMD,and no description of a method of reducing VR sickness that is suitablefor such a case is provided.

This disclosure has been made in view of the above-mentioned, anddescribes a method of providing a virtual space image to be visuallyrecognized by a user to an HMD, and a system therefor, which are devisedfor reducing VR sickness, and are particularly suitable for a case wherea user's visual field in a VR space is synchronized with the movement ofthe HMD.

A basic mode of this disclosure relates to a method of providing avirtual space image to be visually recognized by a user to a headmounted display. The method includes acquiring a rotational directionand a rotational speed of the head mounted display. The method furtherincludes setting a direction of performing image information amountreduction processing based on the rotational direction, and setting arange and an intensity of performing the image information amountreduction processing based on the rotational speed. The method furtherincludes performing the image information amount reduction processing ina virtual space to be visually recognized by the user based ondisplacement of the head mounted display, to thereby generate an imagehaving a reduced image information amount. The “image information amountreduction processing” of this disclosure means processing for reducingan image information amount in a virtual space image to be visuallyrecognized by the user wearing the HMD. The image information amountreduction processing includes various types of image processing forreducing the image information amount, such as blurring an image,reducing contrast, and reducing chromaticity information.

According to this disclosure, the VR sickness can be reduced oreliminated under a visibility state in which the user's visual field inthe VR space is synchronized with the movement of the HMD. Further, evenif the resolution of the HMD is further increased in the future, theoccurrence of the VR sickness due to the increased resolution can beeffectively reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of a method according to at least one embodimentof this disclosure.

FIG. 2 is a conceptual diagram of a hardware configuration of an entiresystem including at least one embodiment of this disclosure.

FIG. 3 is a block diagram of an image generating device according to atleast one embodiment of this disclosure.

FIG. 4A is a schematic diagram of movement of a head of a user.

FIG. 4B is a schematic diagram of a relationship between positiontracking performed by a sensor and a virtual camera arranged in avirtual space.

FIG. 5 is a flow chart of a method of at least one embodiment of thisdisclosure.

FIG. 6A is a schematic diagram of a mode example of an image generatedby blurring an image, which is one mode of image information amountreduction processing, in a horizontal direction of a virtual realityspace when an angular velocity is generated at a yaw angle due torotation of the HMD about a Y axis.

FIG. 6B is a schematic diagram of a mode example of an image generatedby blurring an image, which is one mode of the image information amountreduction processing, in a vertical direction of the virtual realityspace when an angular velocity is generated at a pitch angle due torotation of the HMD about an X axis.

FIG. 6C is a schematic diagram of a mode example of an image generatedby blurring an image, which is one mode of the image information amountreduction processing, in an HMD displacement direction (obliquedirection in FIG. 6C).

FIG. 7 is a schematic diagram of an example of an intensity of the imageblurring, which is one mode of the image information amount reductionprocessing, and a range of performing the processing of blurring animage.

DETAILED DESCRIPTION

Outlines of embodiments of this disclosure are exemplified and listed asbelow.

[Mode 1]

A method of providing a virtual space image to be visually recognized bya user to a head mounted display. The method includes acquiring arotational direction and a rotational speed of the head mounted display.The method further includes setting a direction of performing imageinformation amount reduction processing based on the rotationaldirection, and setting a range and an intensity of performing the imageinformation amount reduction processing based on the rotational speed.The method further includes performing the image information amountreduction processing in a virtual space to be visually recognized by theuser based on displacement of the head mounted display, to therebygenerate an image having a reduced image information amount.

According to Mode 1, reduction in visibility can be reduced or preventedwhile the VR sickness is reduced.

[Mode 2]

A method according to Mode 1, in which the rotational direction and therotational speed of the head mounted display are acquired by detectingan angular velocity vector in accordance with rotation of the headmounted display.

According to Mode 2, the rotational direction and the rotational speedof the head mounted display can be easily acquired.

[Mode 3]

A method according to Mode 1 or 2, in which the direction of performingthe image information amount reduction processing and/or the intensityof performing the image information amount reduction processing is/areset in a stepwise manner.

According to Mode 3, the image information amount reduction processingcan be easily achieved.

[Mode 4]

A method according to any one of Modes 1 to 3, in which the imageinformation amount reduction processing is inhibited when the rotationalspeed is less than a predetermined value.

According to Mode 4, in particular, reduction in visibility can bereduced or prevented.

[Mode 5]

A method according to any one of Modes 1 to 4, in which the rotationaldirection and/or the rotational speed are/is acquired as a discretevalue.

According to Mode 5, the direction and/or the degree of the imageinformation amount reduction processing can be simply set, and theinfluence of minute fluctuations and the like caused during rotation canbe reduced or avoided.

At least one embodiment of this disclosure relates to a system forachieving each of the above-mentioned methods using a computer.

The system is able to produce actions and effects similar to those ofthe method.

Now, at least one embodiment of this disclosure is described in detailwith reference to the drawings. This disclosure is not to be limited tothe at least one embodiment described below, and is to be interpretedbased on the description of the appended claims. Further, a personskilled in the art can employ other similar embodiments, and can performchange or addition of modes as appropriate without departing from thescope of this disclosure.

This disclosure has been devised schematically based on the followingnew findings.

Now, there is assumed a case where a user is present in a real space andhis or her head is turned in a horizontal direction. When a rotationalspeed is fast (high), a viewing angle is small and a visible range isnarrowed to a line-of-sight direction. Further, a peripheral region tobe visually recognized is blurred due to the effect of motion blur.Thus, the user can acquire information of a natural visual system basedon such a visibility mode, and the amount of information to be acquiredcan be reduced to an extent that causes less visual load, excluding avisible region at a central part.

Meanwhile, also in a virtual reality space to be visually recognized bythe user wearing an HMD, when the following visibility mode can beachieved, the user is expected to acquire information of a relativelynatural visual system similarly to the above-mentioned case in the realspace. Specifically, when an HMD displacement speed is high, the visiblerange is narrowed to the line-of-sight direction, and the direction ofperforming the image information amount reduction processing isdetermined based on the direction of displacement of the head mounteddisplay. Then, the information amount is reduced in the virtual spaceimage to be visually recognized by the user, excluding the visibleregion at the central part. In this manner, the information amount of aregion excluding the visible region at the central part can be reducedto an extent that causes less visual load. Thus, the VR sickness, whichis partially caused by the visual load, can be expected to be reduced.

FIG. 1 is a flow chart of a method according to at least one embodimentof this disclosure based on the new findings described above. The methodincludes Step 2 of acquiring a rotational direction and a rotationalspeed of an HMD. The method further includes Step 3 of setting adirection of performing image information amount reduction processingbased on the rotational direction, and setting a range and an intensityof performing the image information amount reduction processing based onthe rotational speed. The method further includes Step 4 of performingthe image information amount reduction processing in a virtual space tobe visually recognized by the user based on displacement of the HMD, tothereby generate an image having a reduced image information amount.Details of the steps are described later (for example, see thedescription referring to FIG. 5).

FIG. 2 is a conceptual diagram of a hardware configuration of a systemaccording to at least one embodiment of this disclosure. A system 100includes, as the hardware configuration, an HMD 120 and an imagegenerating device 200. The HMD 120 and the image generating device 200are electrically connected to each other by, for example, a cable 150 sothat mutual communication is enabled therebetween. Wirelesscommunication may be used instead of the cable 150.

The HMD 120 is a display device to be used by being worn on a head of auser 101. The HMD 120 includes a display 122 and a sensor 126. The HMD120 may further include a speaker and/or headphones (not shown).

The display 122 is configured to present an image in a field of view ofthe user 101 wearing the HMD 120. For example, the display 122 may beconfigured as a non-transmissive (or partially transmissive) display. Inthis case, the sight of the outside world of the HMD 120 is at leastpartially blocked from the field of view of the user 101, and the user101 can see the image displayed on the display 122. On the display 122,for example, an image generated with use of computer graphics isdisplayed. As an example of the image generated with use of computergraphics, there is given a virtual reality space image obtained byforming an image of a space of virtual reality, for example, a worldcreated in a computer game.

The sensor 126 is a sensor configured to detect the direction ofmovement of the head of the user 101 wearing the HMD 120. Examples ofthe sensor 126 include a magnetic sensor, an angular velocity sensor, anacceleration sensor, or a combination thereof. When the sensor 126 is amagnetic sensor, an angular velocity sensor, or an acceleration sensor,the sensor 126 is built into the HMD 120, and is configured to output avalue (magnetic, angular velocity, or acceleration value) based on thedirection or the movement of the HMD 120. By processing the value outputfrom the sensor 126 by an appropriate method, the direction of movementof the head of the user 101 wearing the HMD 120 is calculated. Thedirection of the head of the user 101 can be used to change a displayimage of the display 122 so as to follow the movement of the head of theuser 101 when the head is moved. For example, when the user 101 turnshis or her head to the right (or left, upper, or lower) side, thedisplay 122 displays a virtual view that is present in the right (orleft, upper, or lower) direction of the user in the virtual realityspace.

As the sensor 126, a sensor provided outside of the HMD 120 may beemployed. For example, the sensor 126 may be an infrared sensor that isinstalled separately from the HMD 120 at a fixed position in the room.The infrared sensor may be used to detect an infrared reflective markerformed on the surface of the HMD 120, to thereby specify the directionof the head of the user 101 wearing the HMD 120.

The image generating device 200 is a system for generating an image tobe displayed on the HMD 120. The image generating device 200 includes atleast, as the hardware configuration, a processor 202, a memory 204, auser input interface 206, and a communication interface 208. The imagegenerating device 200 may be a dedicated device, but, for example, theimage generating device 200 may be achieved as a personal computer, agame console, a smart phone, a personal digital assistant (PDA), or atablet terminal.

The memory 204 has stored therein at least an operating system and animage generating program. The operating system is a computer programcontaining instructions for controlling the entire operation of theimage generating device 200. The memory 204 can further temporarily orpermanently store data generated by the operation of the imagegenerating device 200. Specific examples of the memory 204 include aread only memory (ROM), a random access memory (RAM), a hard disk, aflash memory, and an optical disc.

The processor 202 is configured to read out instructions stored in thememory 204, to thereby execute processing in accordance with theinstructions. The processor 202 executes the instructions stored in thememory 204, to thereby generate an image to be displayed on a screen.The processor 202 includes a central processing unit (CPU) and agraphics processing unit (GPU).

The user input interface 206 is configured to receive input foroperating the image generating device 200 from the user of the system100. Specific examples of the user input interface 206 include a gamecontroller, a touch pad, a mouse, and a keyboard.

The communication interface 208 is a network interface for communicatingto/from another device via a network.

The image generating system may be constructed as a set of instructionsindependent from an SNS platform, or may be constructed as a set ofinstructions to be provided on the SNS platform. In the case of the setof instructions to be provided on the SNS platform, the set ofinstruction is implemented on a server, and the server executescalculation processing or data processing for image generation inaccordance with input operation of each user. Therefore, in such a case,storing the image generating instructions in the memory 204 is avoidedin at least one embodiment.

Next, a basic operation of the image generating device 200 is described.In the following description, the virtual space means a virtual reality(VR) space.

FIG. 3 is a block diagram of an image generating device 200 according toat least one embodiment, which represents functions for the imagegeneration processing to be achieved by the processor 202 illustrated inFIG. 2 reading out and executing the image generating instructionsstored in the memory 204.

An image generating unit 231 is configured to generate an image to bedisplayed on the HMD 120. For example, the image generating unit 231acquires predetermined data from a storage unit 220, to thereby generatean image by computer graphics processing based on the acquired data. Asat least one example, the image generating unit 231 may generate such avirtual reality space image that the second user 101 wearing the HMD 120can recognize a virtual reality space of a computer game. The virtualreality space image represents an image that the user can see in thevirtual reality space. For example, the virtual reality space image tobe generated by the image generating unit 231 includes various objectssuch as characters that appear in a computer game, landscape includingbuildings and trees, interior decorations including furniture and wallsin a room, items on the ground, a part (hand or foot) of a body of anavatar (user himself or herself) to be operated by the user, or anobject (gun or sword) held by the avatar. Data necessary for generatingthe virtual reality space image, such as arrangement positions, shapes,and colors of the above-mentioned objects constructing the virtualreality space, is stored in the storage unit 220 as virtual realityspace constructing information 221. The image generating unit 231 isconfigured to generate such a virtual reality space image of a computergame based on the virtual reality space constructing information 221acquired from the storage unit 220.

Further, the image generating unit 231 is configured to change an imagebased on the output value from the sensor 126. For example, the image tobe generated by the image generating unit 231 may be an imagerepresenting a state in which the field of view of the user in thevirtual reality space transitions so as to follow the movement of thehead of the user 101, which is represented by the output value from thesensor 126. As an example, FIG. 4A is a schematic illustration of themovement of the head of the user. As illustrated in FIG. 4A, an axisconnecting between the center of the head of the user 101 and the centerof the HMD 120 (center of the screen of the display 122) is set as a Zaxis, an axis connecting between the center of the head of the user 101and the top of the head is set as a Y axis, and an axis passing throughthe center of the head of the user 101 and being orthogonal to the Yaxis and the Z axis is set as an X axis. When the sensor 126 is, forexample, an angular velocity sensor, the sensor 126 outputs values ofrespective angular velocities of a pitch angle about the X axis, a yawangle about the Y axis, and a roll angle about the Z axis. The imagegenerating unit 231 changes the virtual reality space image based on theoutput values of those angular velocities, that is, the direction of thehead of the user 101. For example, when the user 101 turns his or herhead to the right, the yaw angle about the Y axis is changed. The imagegenerating unit 231 changes the virtual reality space image so that theview in the right direction of the user in the virtual reality space isdisplayed in accordance with the change in angular velocity value aboutthe Y axis. Similarly, when the user 101 inclines his or her head to theright, the roll angle about the Z axis is changed. The image generatingunit 231 changes the virtual reality space image so that the field ofview of the user in the virtual reality space is inclined to the rightin accordance with the change in angular velocity value about the Zaxis.

Further, the image generating unit 231 is configured to change the imagebased on the position of the user. For example, when the user walksaround in the virtual reality space, the image to be generated by theimage generating unit 231 may be an image representing a view to be seenby the user from a position at which the user is currently standing inthe virtual reality space. As an example, information of the temporalposition of the user in the virtual reality space is stored in thestorage unit 220. The image generating unit 231 acquires the latestinformation of the position of the user in the virtual reality spacefrom the storage unit 220. In addition, from the user input interface206, for example, a game controller, instructions of a moving directionand a moving speed of the user are input as operation input for the userto walk around in the virtual reality space. The image generating unit231 calculates the current position of the user in the virtual realityspace based on the latest information of the position of the user, whichis acquired from the storage unit 220, and on the information of themoving direction and the moving speed of the user, which is input fromthe user input interface 206. The image generating unit 231 changes thevirtual reality space image based on the calculated current position ofthe user so that the field of view of the user changes in accordancewith the user walking in the virtual reality space.

FIG. 4B is a schematic diagram of a relationship between positiontracking performed by the sensor 126 and a virtual camera 404 arrangedin a virtual space 402. The position tracking means a function ofdetecting information relating to the position and the inclination ofthe HMD 120 with use of the sensor 126.

In FIG. 4B, the virtual camera 404 is arranged at a predeterminedposition in the virtual space 402, and the sensor 126 is virtuallyarranged outside of the virtual space 402 (in the real space). Afield-of-view region 408 is a part (field-of-view image 418) forming auser's field of view in a virtual space image 410. The field-of-viewregion 408 is determined based on a reference line of sight 412, and thereference line of sight 412 is determined based on the position and theinclination of the virtual camera 404. In this manner, the virtualcamera 404 arranged at a predetermined position in the VR space being athree-dimensional virtual space is controlled in accordance with themovement of the head of the user being a wearer of the HMD 120, and theimage (field-of-view image 418) in the field-of-view region 408 acquiredby the virtual camera 404 is visually recognized by the user. Thefield-of-view region 408 to be visually recognized by the user isdetermined based on the reference line of sight 412 of the virtualcamera 404, and the movement of the HMD 120 is associated with themovement of the virtual camera 404 so that the reference line of sight412 matches with the Z-axis direction (see FIG. 4A) of the HMD 120.

As described above, the image generating unit 231 generates the virtualreality space image in accordance with the position and the headdirection of the user in the virtual reality space. The generatedvirtual reality space image is output to the HMD 120 via the imageoutputting unit 239, and is displayed on the display 122. With this, theuser can see the virtual view present in the direction in which the headis directed from the position at which the user is currently standing inthe virtual reality space.

Next, an outline of one example of processing of at least one embodimentof this disclosure is described based on examples illustrated in FIG. 5,FIG. 6A, and FIG. 6B. FIG. 5 is a flow chart of a method of processingoperations of at least one embodiment of this disclosure. Further, FIG.6A is a schematic diagram of a mode example of a case of blurring animage, which is one mode of the image information amount reductionprocessing, in the horizontal direction of the virtual reality space,FIG. 6B is a schematic diagram of a mode example of a case of blurringan image, which is one mode of the image information amount reductionprocessing, in the vertical direction of the virtual reality space, andFIG. 6C is a schematic diagram of a mode example of an image generatedby blurring an image, which is one mode of the image information amountreduction processing, in an HMD displacement direction (obliquedirection in FIG. 6C).

First, respective angular velocities ωX, ωY, and ωZ of the pitch angleabout the X axis, the yaw angle about the Y axis, and the roll angleabout the Z axis, which are output from the angular velocity sensor 126(see FIG. 2) of the HMD, are detected (S501).

In at least one embodiment, the detected angular velocities ωX, ωY, andωZ are subjected to discretization processing (S502). The discretizationprocessing means replacing the detected angular velocities ωX, ωY, andωZ being data having continuous values by discontinuous numerical values(discrete values). Such discretization processing is a method effectivefor avoiding influence of fluctuations when there are minutefluctuations in the angular velocities ωX, ωY, and ωZ. The discretevalues obtained through the discretization do not necessarily have equalintervals. For example, discretization of regarding a detected valuethat is less than a predetermined value as “0” or discretization ofsegmenting a predetermined range may be employed as appropriate.

A three-dimensional angular velocity vector Ω having the respectiveangular velocities ωX, ωY, and ωZ as components is determined based onthe angular velocities ωX, ωY, and ωZ. Then, a magnitude, i.e., anabsolute value, |Ω| and a direction Ω/|Ω| of the angular velocity vectorΩ are acquired (S503).

In at least one embodiment, the angular velocity vector Ω is subjectedto discretization processing with respect to the magnitude |Ω| anddirection Ω/|Ω| (S504). The discretization processing is, as describedabove, a method effective for avoiding influence of fluctuations whenthere are minute fluctuations in the magnitude |Ω| and the directionΩ/|Ω| of the angular velocity vector Ω. As described above, in at leastone embodiment, the discrete values obtained through the discretizationdo not have equal intervals.

Next, whether or not the magnitude |Ω| of the angular velocity vector Ωis less than a predetermined value is determined (S505). When the resultof the determination is positive, the processing for blurring an imageis inhibited. Further, when the result of the determination is negative,the processing proceeds to the following step.

Next, a direction of performing the processing of blurring an image isset based on the direction Ω/|Ω| of the angular velocity vector Ω(direction of displacement of the HMD), and an intensity of the imageblurring and a range of performing the processing of blurring an imageare set based on the magnitude |Ω| of the angular velocity vector Ω(S506). The intensity of blurring means the degree of the blurring ofthe image, that is, the degree of reducing the image information amount.

The above-mentioned setting of the intensity of the image blurring andthe range of performing the processing of blurring an image is describedwith reference to FIG. 7. FIG. 7 is a schematic diagram of an example ofthe intensity of the image blurring and the range of performing theprocessing of blurring an image. FIG. 7 includes an example of a methodinvolving increasing a range of a peripheral region to be subjected tothe processing of blurring an image and increasing the intensity of theimage blurring in the peripheral region as the HMD displacement speed isincreased, to thereby achieve a natural visibility mode.

FIG. 7 is a diagram of a case where the HMD displacement direction is ahorizontal direction of FIG. 7, in which part (β) represents a range ofthe peripheral region to be subjected to the processing of blurring animage in the visible range. Further, in part (α), on the left and rightsides of the center of the visible range, the intensity of the imageblurring is represented by a solid line A, a dashed-dotted line B, and abroken line C. In this case, the solid line A, the dashed-dotted line B,and the broken line C correspond to cases of a high HMD displacementspeed, a middle HMD displacement speed, and a low HMD displacementspeed, respectively, and schematically indicate the intensity of theimage blurring in the peripheral region in accordance with the magnitudeof the HMD displacement speed. As is apparent from FIG. 7, as the HMDdisplacement speed is increased, the range of the peripheral region tobe subjected to the processing of blurring an image is increased, andthe intensity of the image blurring in the peripheral region is alsoincreased. The reason why the intensity of the image blurring isincreased toward the end is for changing an image from a state in whichthe processing of blurring an image is not performed so as to generallysubject the image to the processing of blurring an image, to therebyprovide a natural visibility mode to the user wearing the HMD. Further,in order to obtain an effect of image blurring in accordance with theHMD displacement speed, the solid line A, the dashed-dotted line B, andthe broken line C have different slopes. In FIG. 7, the solid line A,the dashed-dotted line B, and the broken line C are indicated in astraight-line mode, but the lines are not necessarily limited tostraight lines. A curved-line mode or a mode of change in a stepwisemanner may be employed in at least one embodiment.

Then, the processing of blurring an image is performed based on thedisplacement of the HMD, and thus an image having a reduced imageinformation amount is generated in the virtual space to be visuallyrecognized by the user (S507).

Specific examples of images obtained by the processing of Step S507 aredescribed in detail with reference to FIG. 6A, FIG. 6B, and FIG. 6C.FIG. 6A is a schematic diagram of a mode example of an image generatedby blurring an image in the horizontal direction of the virtual realityspace when an angular velocity is generated at the yaw angle due torotation of the HMD about the Y axis. Further, FIG. 6B is a schematicdiagram of a mode example of an image generated by blurring an image inthe vertical direction of the virtual reality space when an angularvelocity is generated at the pitch angle due to rotation of the HMDabout the X axis. Further, FIG. 6C is a schematic diagram of a modeexample of an image generated by blurring an image in the HMDdisplacement direction (oblique direction in FIG. 6C).

First, description is made of the mode example in FIG. 6A of the imagegenerated by blurring an image in the horizontal direction of thevirtual reality space when an angular velocity is generated at the yawangle due to rotation of the HMD about the Y axis. In the mode exampleof FIG. 6A, the angular velocity is generated at the yaw angle due tothe rotation of the HMD about the Y axis, and hence the degree of theimage blurring in the horizontal direction and the range of performingthe processing of blurring an image are set based on the magnitude ofthe angular velocity. Specifically, there is assumed a case where themagnitude of the angular velocity is at a stage of “middle” among thethree stages of high, middle, and low, and the width of the peripheralregion to be subjected to the processing of blurring an image is set tothe middle stage among the three stages of large, middle, and smallbased on the middle-stage magnitude of the angular velocity. Inaddition, the intensity (degree) of the image blurring in the peripheralregion is set to the middle stage among the three stages of high,middle, and low. With such a configuration, as described above, the usercan acquire information of a relatively natural visual system, and theacquired information amount can be reduced to an extent that causes lessvisual load. Therefore, the VR sickness, which is partially caused bythe visual load, can be reduced.

In the mode example of FIG. 6A, as the magnitude of the angular velocityis increased or decreased, the width of the peripheral region to besubjected to the processing of blurring an image and the degree of theimage blurring can also be increased or decreased.

Next, description is made of the mode example in FIG. 6B of the imagegenerated by blurring an image in the vertical direction of the virtualreality space. In the mode example of FIG. 6B, the angular velocity isgenerated at the pitch angle due to the rotation of the HMD about the Xaxis, and hence the degree of the image blurring in the verticaldirection and the range of performing the processing of blurring animage are set based on the magnitude of the angular velocity.Specifically, there is assumed a case where the magnitude of the angularvelocity is at a stage of “middle” among the three stages of high,middle, and low, and the width of the peripheral region to be subjectedto the processing of blurring an image is set to the middle stage amongthe three stages of large, middle, and small based on the middle-stagemagnitude of the angular velocity. In addition, the intensity (degree)of the image blurring in the peripheral region is set to the middlestage among the three stages of high, middle, and low. With such aconfiguration, as described above, the user can acquire information of arelatively natural visual system, and the acquired information amountcan be reduced to an extent that causes less visual load. Therefore, theVR sickness, which is partially caused by the visual load, can bereduced.

Also in the mode example of FIG. 6B, as the magnitude of the angularvelocity is increased or decreased, the width of the peripheral regionto be subjected to the processing of blurring an image and the degree ofthe image blurring can also be increased or decreased.

Next, description is made of the mode example in FIG. 6C of the imagegenerated by blurring an image in the HMD displacement direction. Ingeneral, the displacement of the HMD causes rotation about the X axis,the Y axis, and the Z axis of the HMD, and hence the angular velocity isgenerated at each of the pitch angle about the X axis, the yaw angleabout the Y axis, and the roll angle about the Z axis due to thedisplacement of the HMD. In this case, the angular velocity vectorhaving the pitch angle about the X axis, the yaw angle about the Y axis,and the roll angle about the Z axis as components is obtained. Then, thedirection of performing the processing of blurring an image can bedetermined based on the direction of the angular velocity vector, andthe width of the peripheral region to be subjected to the processing ofblurring an image and the intensity (degree) of the image blurring canbe determined based on the magnitude of the angular velocity vector.

In FIG. 6C, the HMD displacement direction (direction of the angularvelocity vector) has horizontal and vertical components on the screen,and hence the direction of performing the processing of blurring animage is an oblique direction on the screen. In FIG. 6C, there isassumed a case where the magnitude of the angular velocity vector is ata stage of “middle” among the three stages of high, middle, and low, andthe width of the peripheral region (region in the oblique direction) tobe subjected to the processing of blurring an image is set to the middlestage among the three stages of large, middle, and small based on themiddle-stage magnitude of the angular velocity. In addition, theintensity (degree) of the image blurring in the peripheral region is setto the middle stage among the three stages of high, middle, and low.With such a configuration, as described above, the user can acquireinformation of a relatively natural visual system, and the acquiredinformation amount can be reduced to an extent that causes less visualload. Therefore, the VR sickness, which is partially caused by thevisual load, can be reduced.

Also in the mode example of FIG. 6C, as the magnitude of the angularvelocity vector is increased or decreased, the width of the peripheralregion to be subjected to the processing of blurring an image and theintensity (degree) of the image blurring can also be increased ordecreased. Further, the direction of performing the processing ofblurring an image can be determined based on the HMD displacementdirection, and an image having a reduced information amount can begenerated in the virtual space image to be visually recognized by theuser.

While the description has been made above on at least one embodiment ofthis disclosure, this disclosure is not limited thereto, and variousmodifications can be made thereto without departing from the scope ofthis disclosure.

What is claimed is:
 1. A method comprising: generating a virtual spaceimage for displaying on a head mounted display (HMD); acquiring arotational direction and a rotational speed of the HMD; and subjectingthe virtual space image to blurring processing based on the rotationaldirection and the rotational speed, the blurring processing beingperformed on an end region of the virtual space image on at least oneside of the virtual space image in a direction corresponding to therotational direction, a size of the end region is based on therotational speed, and an intensity of blurring of the end region isbased on the rotational speed.
 2. The method according to claim 1,wherein the rotational direction and the rotational speed of the HMD areacquired by detecting an angular velocity vector in accordance withrotation of the HMD.
 3. The method according to claim 1, wherein thedirection of the blurring processing or the intensity of the blurringprocessing is set in a stepwise manner.
 4. The method according to claim1, wherein the blurring processing is inhibited when the rotationalspeed is less than a predetermined value.
 5. The method according toclaim 1, wherein the rotational direction or the rotational speed isacquired as a discrete value.
 6. A system comprising: a processor; anon-transitory computer readable medium connected to the processor,wherein the non-transitory computer readable medium is configured tostore instructions for execution by the processor to: generate a virtualspace image for displaying on a head mounted display (HMD); acquire arotational direction and a rotational speed of the HMD; and subject thevirtual space image to blurring processing based on the rotationaldirection and the rotational speed, the blurring processing beingperformed on an end region of the virtual space image on at least oneside of the virtual space image in a direction corresponding to therotational direction, a size of the end region is based on therotational speed, and an intensity of blurring of the end region isbased on the rotational speed.